The happy find came last year during an investigation into an alleged drug ring. Officers were using Google Earth to find the addresses of a couple of farmers suspected of involvement in the operation, and "quickly spotted" the 7,500 m2 illicit horticultural site in the northeastern canton of Thurgau.

Norbert Klossner, the head of Zurich police's narcotics unit, said: "It was an interesting chance discovery."

The cops' drug-busting dragnet resulted in the arrest of 16 people and the seizure of 11.1 tonnes of marijuana plus 900,000 Swiss francs ($780,000) in cash and valuables. According to officials, the gang is "alleged to have sold up to seven tonnes of hashish and marijuana between 2004 and 2008, with an annual turnover of 3-10 million francs a year". ®